Spatial selection in captive adult female chimpanzees

Spatial selection refers to an animal's frequent use of certain areas of its enclosure or range. Through differential use of habitat, an individual can limit the amount of time spent in close proximity to other group members. The four adult female chimpanzees at the Tulsa Zoo were studied to determine if they used their enclosure differently from one another, if each had selected areas it occupied most frequently, and if an individual's preferred area was used by other female group members. Pairwise comparisons showed that the females used their island habitat differently from one another with the exception of one pair. Although these two females overlapped in their use of the enclosure, they separated their use temporally, thereby reducing the amount of time spent in close proximity to one another. Each female had a selected site that she occupied more frequently than did the other females. However, there was variation in the extent to which the females occupied each other's selected sites. Time of day and temperature had no effect on use of the habitat, however, one female showed a seasonal variation in her use of the enclosure. The spatial selection exhibited by these females may be comparable to the use of core areas by wild female chimpanzees. © 1994 Wiley-Liss, Inc.     

Reproductive function in aged female chimpanzees.

Reproductive function was evaluated in ten female chimpanzees (Pan troglodytes) aged 35-48 years. Forty-eight years is the longevity record for the chimpanzee. Data on cycle frequency and duration was available for seven animals. Most were cycling regularly until death, and all had experienced at least one menstrual cycle within one year of death. After exclusion of periods when the animals were pregnant or in postpartum amenorrhea, the mean cycle frequency (+/- standard error)/year was 9.54 +/- 0.20 in seven animals aged 15-25 (432 cycles analyzed) compared to 8.6 +/- 0.76 in the same animals at age 35 + years (405 cycles analyzed); this effect approached significance (p = 0.072, Mann-Whitney U-test). Cycle length of 16 cycles in each of seven animals aged 15-25 was 32.23 +/- 0.38 days. The same animals when aged over 35 had mean cycle lengths of 35.59 +/- 0.73. This difference was not significant, although cycle lengths clearly increased with age in some individual animals. In five aged animals for which mating data was available, appropriate exposure to a male occurred in 52 cycles, but only two pregnancies occurred; one pregnancy resulted in a live birth at age 38, the other in a stillbirth at age 40. This conception rate was 3.85% compared with 20% in the same animals aged 15-25. These data suggest greatly reduced fertility after age 35, although menstrual cycle frequency remained high. The persistence of menstrual cyclicity until death, which occurred due to natural causes at latest in the fifth decade, is in striking contrast to the human female in which menopause occurs in the fifth decade and death is often postponed for several more decades.     

Greeting behavior during party encounters in captive chimpanzees

Party encounter situations were experimentally produced in a group of captive chimpanzees (Pan troglodytes verus) at the Primate Research Institute of Kyoto University, Japan. During weekends all subjects (two adult males and five adult females) usually stayed together in the rooms (Baseline condition). Under experimental conditions, we shut passages between rooms to divide the subjects into two groups. We examined the effects of temporal separation of group members on affiliative interactions, aggressive interactions, and simple proximity. The frequency of affiliative interactions between male and female chimpanzees and between female chimpanzees increased when they encountered one another after separation, irrespective of male identity or housing history. Therefore we considered affiliative interactions between males and females during party encounters as being the response between separated individuals. The same tendency was not found in the frequency of affiliative interactions between females or between males. Unlike affiliative interactions, neither aggressive interactions nor simple proximity were influenced by separation.     

Procedures for improving maternal behavior in captive chimpanzees

Captive female chimpanzees who have had no opportunity to observe mothers with infants or to interact with infants often show inappropriate maternal behavior, particularly with their first-born infant, and this usually results in the removal of the infant to be human-reared. The present study used two techniques to encourage appropriate maternal behavior in ten pregnant female chimpanzees. These females were housed together with unrelated infant chimpanzees to adopt, or with lactating female chimpanzees and infants to observe. In five cases both techniques were used, in two cases only the first technique was used, and in three cases only the second technique was used. All ten female chimpanzees showed appropriate maternal behavior when their infants were born, in contrast to a group of eight female chimpanzees who had no such experience whose infants had to be removed for human-rearing. It is suggested that these techniques, or adaptations of them, could be applied to many other captive female chimpanzees with similar results.     

Sleeping behavior and associations in a group of captive chimpanzees.

The present study investigated the sleeping behavior and preferences of a group of six adolescent chimpanzees at the Delta Regional Primate Research Center in Louisiana, USA. The study sought to relate sleeping partner preferences to other aspects of social relationships. Comparative observations between those chimpanzee behaviors seen in the wild and in this group are noted.     

Mother-infant relations and infant development in captive chimpanzees and orang-utans

Four chimpanzee (Pan troglodytes)mother—infant dyads and four orangutan (Pongo pygmaeus)motherinfant dyads were studied for the first 11 months of the infants’ lives. For both species, ventroventral contact and nipple contact decreased over time at a similar rate, but total contact decreased earlier in the orangutans and was 50% lower than for the chimpanzees at the end of the study. Social play between the mothers and the infants did not differ in frequency between the species, but orangutans played above the ground and chimpanzees on the ground. Solitary play differed in form between the species and, like social play, reflected their differences in arboreal and terrestrial proclivities. In addition, the orangutans engaged in solitary play considerably more frequently than the chimpanzees during the second half-year of life. The developmental differences in mother-infant contact and solitary play of these apes are consistent with the differences in their speciestypical social organization. The data may reflect, therefore, early development of species differences in the social and relatively solitary natures of chimpanzees and orangutans, respectively. An erratum to this article is available at .     

Reproductive biology of captive female Eurasian lynx, Lynx lynx

Studies on wild Eurasian lynx (Lynx lynx) have revealed variation in reproduction between areas, years and individuals. In order to explore potential causes for this variation other than food supply, we analysed data from captive lynx, which provide conditions with minimal environmental variation as all were fed ad libitum. Data from 37 individual female lynx were available from 20 zoos in Norway, Sweden, Finland, Switzerland and the Czech Republic. Data on 177 reproductive events (where a male was available to the female at mating time) are presented. Of these events, 85% resulted in litters being born. Average litter size was 1.95, with a variation from 1 to 4. The mean birth date was 26th May, and sex ratio was not significantly different from parity. The probability of reproduction was related to age, with fewer litters produced by the very young (2–3-year old), and no sign of a senescence effect. However, a clear effect of senescence on litter size was evident. The captive lynx did not have higher reproductive rates than wild lynx, indicating that either factors other than food supply are driving the variation in wild lynx reproduction, or that a factor such as stress may be causing additional variation in the captive population.     

Mortality of wild and captive chimpanzees

Mortality of chimpanzees in the wild (Gombe National Park) and in captivity (Taronga Zoo, Sydney and Melbourne Zoo) was compared using standard cohort life table techniques. Overall mortality probabilities up to age 30 were compared using a logrank test. No significant difference in overall mortality was revealed, and the mortality curves did appear to be surprisingly similar, but there were nevertheless some differences in the distribution of mortality. Perinatal mortality was higher in the zoo, while post-perinatal and infant mortality were higher in the wild. Survivorship in the older zoo animals (over age 27) was better than the wild. These differences were attributed to the more sheltered zoo environment, including the availability of veterinary care, which could be expected to improve survival in infants and older adults. The higher perinatal mortality experienced by zoo infants could be reflecting higher levels of inbreeding among the zoo animals.     

Reproductive behavior in captive California condors (Gymnogyps californianus)

From the fall of 1987 to the spring of 1994, data on reproductive behavior were collected on seven different pairs of California condors (Gymnogyps californianus) housed at the San Diego Wild Animal Park. Behavioral data were collected from videotaped activities in their flight pens. Behaviors for this report include male and female displays and incomplete and complete copulations. Data on the time it took for females to recycle and lay another egg after egg removal were acquired from the California Condor Studbook. Male display rates were significantly higher than female rates throughout the breeding season. Males began displaying 52–132 days before the start of copulations. Copulations slowly increased from Day -51 and peaked ∼ Day -8, prior to egg laying. Female display rates were significantly more frequent at the end of the season after the last egg was laid. An average of 26.8 (±3.1 SEM) copulations occurred prior to egg laying. Copulations occurred throughout the day, with the higher mean percentages occurring between 0700 and 0900 hours. After egg removal, the interval between laying of the first and second eggs and between the second and third eggs had a mean of 34.1 (±10.1 SD) days. © 1996 Wiley-Liss, Inc.     

Successful feeding enrichment for captive chimpanzees

An analysis of a feeding enrichment program for captive chimpanzees was completed to determine the effects of that program on the incidence of agonistic and abnormal behaviors by using 41 adult chimpanzees in six social groups. Four feeding enrichment procedures were implemented simultaneously in the experimental phase of this ABA design study. The procedures were planned to elicit time-consuming, noncompetitive feeding, theorizing a consequent reduction in agonism and detrimental abnormal behaviors typically occurring in captive chimpanzees. The 270 hours of data were collected over a 6-month period. A multivariate analysis of variance result supported the hypothesis, as the barrage of feeding enrichment techniques significantly reduced agonism and abnormal behaviors. This study's significance lies in its application of the scientific method to improving the husbandry of captive primates.     

The neighbor effect: Other groups influence intragroup agonistic behavior in captive chimpanzees

While intercommunity interactions are well documented in wild chimpanzees, the influence of neighboring captive groups on social behavior has not been investigated. This study examined the influence of vocalizations and noisy displays produced in neighboring groups (i.e., “neighbor vocalization”) on intragroup hooting, bluff displays, and agonistic behavior. Chimpanzees from two broadly differing housing conditions were selected in order to examine the effect of neighboring groups: “Wing Groups” (those living in indoor/outdoor pens with auditory access to large number of neighboring individuals) and “Building Groups” (those housed in one indoor building, able to hear the calls and noisy displays produced by a small number of neighboring individuals occupying the building). Data were collected on 58 adult and juvenile subjects living in social groups varying in size from two to 14 individuals. Observation sessions were divided into two categories depending on the level of neighbor vocalization. Wing Groups showed higher rates of hooting, bluff displays, and agonistic behavior against other group members when levels of neighbor vocalization were high. Building Groups showed the same pattern, with results for bluff displays reaching statistical significance. This effect was also found through an analysis of the time periods immediately surrounding incidents of neighbor vocalization: Hooting and bluff displays were significantly more common after than before neighbor vocalizations. In spite of variation between the two housing conditions with respect to overall levels of neighbor vocalization, degree of differences between the high and low vocalization levels, and methods of data collection, a consistent neighbor effect was detected. This effect is congruous with behavioral patterns observed in the wild, and is therefore considered an expression of species-typical behavior as opposed to an artifact of captivity. These results are relevant to captive management, and bear on the influence of housing condition on psychological well-being. © 1996 Wiley-Liss, Inc.     

Model life table for captive chimpanzees

Mortality statistics from three captive populations of chimpanzees (Pan troglodytes) were combined to generate standard model life tables for each sex in this species. The model is compared to an estimate of survivorship of a group of wild animals, and is applied to an incomplete data set to illustrate how the model may be used to extend estimates of mortality statistics to missing older ages. © 1995 Wiley-Liss, Inc.     

Feeding enrichment and body weight in captive chimpanzees

Although positive behavioral consequences have been attributed to feeding enrichment, physiological changes may also occur. In this study, the body weight records of a large chimpanzee colony were reviewed to determine if body weight was affected by the implementation of a daily enrichment program, including food items offered three to four times per week. Comparing the mean body weight by age groups indicated that the weight of female chimpanzees was significantly greater after feeding enrichment but that male body weight did not differ.     

Behavioral changes during weaning in captive chimpanzees

Behavioral changes during weaning of chimpanzee infants in captive social groups were compared with those of infants in the natural habitat. Results of the weaning process were the same for the mother-infant pairs in captivity and the natural habitat, i.e., an infant independent of suckling, regular maternal transport and sleeping with the mother. The captive infants, however, did not respond to weaning with depression or regression to infantile behaviors as did infants in the natural habitat. Quite probably the social and physical environmental differences between the two habitats faciliated a less stressful weaning period for the captive mother-infant pairs.     

Destructible toys as enrichment for captive chimpanzees

The use of destructible objects or toys as enrichment for nonhuman primates has had promising results in terms of increased use and positive behavioral effect. The purpose of this project was to determine the use and durability of a number of inexpensive, destructible toys provided one at a time or several at once. Nine singly caged chimpanzees were provided with 8 different toys made of plastic, vinyl, or cloth, and the frequency of use of the toys was determined during 15 min trials 2 times per day. A toy was removed when it was destroyed or when it was not contacted during 4 trials. The chimpanzees contacted the toys an average of 11 times per trial, and the use of the individual toys was significantly higher when provided 1 at a time rather than all at once. Use of the toys was fairly stable over time, and the toys remained in the cages an average of 3.2 days. The durability of the toys was related to the type of toy (e.g., more flexible cloth and vinyl toys lasted longer than rigid plastic toys). The destructible toys were used significantly more often than other permanent cage toys or televisions. Toy use was not related to age, level of abnormal behavior, or use of existing permanent toys or television. The implications of the results were related to the management of an environmental enrichment program and indicated that the provision of flexible, inexpensive toys 1 at a time can be an effective method of enrichment for captive chimpanzees.     

The acquisition of stone-tool use in captive chimpanzees

In order to investigate the acquisition of stone-tool use to crack nuts, experiments were conducted with five captive chimpanzees, employing combinations of trial-and-error, and three types of observation learning of varied difficulty. Two adults and one sub-adult succeeded in acquiring this behavior in the tests where tool use was demonstrated by the experimenter, or by a successful chimpanzee. Analysis of their behavior patterns showed the adults' and sub-adult's process to success to be divided into three stages; these can be characterized as trial-and-error, understanding of the method, and learning the technique, respectively. A factor for distinguishing success from failure is whether or not a subject observes demonstrations with interest in the behavior itself. This interest, in turn, depends on the intensity of the desire for nuts. When released, the successful chimpanzees practiced the same behavior in a group of chimpanzees, and the behavior newly diffused to an infant. Unlike the adults, the infant did not go through the staged process but reached the solution through goal-directed trial-and-error.     

Reproductive synchrony in captive macaques

Captive bonnet macaques housed at the California Primate Research Center reproduce seasonally. The chances of producing surviving infants were substantially reduced among females who conceived at the peak of the mating season compared with females whose conceptions were more isolated in time. Primiparous females and low ranking females were most consistently affected by the extent of reproductive synchrony. Behavioral data suggest that harassment of conceiving and pregnant females may have contributed to the correlation between the extent of reproductive synchrony and infant mortality as the levels of aggression toward females were highest during the months in which conceptions were most common.     

Reproductive experience alters anxiety-like behavior in the female rat

Reproductive experience (i.e. pregnancy and lactation) results in significant alterations in subsequent hormone levels in female rats. Several studies have demonstrated that circulating hormones can significantly affect anxiety-like behavior. Thus, the purpose of the present study was to determine whether reproductive experience induces alterations in anxiety-like behaviors in cycling female rats and in older, reproductively senescent rats. In Experiment 1, the elevated plus maze (EPM) was used to test young cycling (6-8 weeks post-weaning) and middle-aged (32-36 weeks post-weaning) primiparous rats and their age-matched nulliparous counterparts for anxiety-like responses. In Experiment 2, activity in the open field was used as an additional measure of anxiety-like behavior in young (proestrus) and middle-aged (constant estrus) primiparous and nulliparous rats. For Experiment 3, EPM testing was conducted in separate groups of young and middle-aged animals tested two weeks after ovariectomy. The results revealed that during proestrus, primiparous animals exhibited fewer anxiety-like behaviors on the EPM compared to nulliparous controls. In middle-aged animals, however, parity was associated with increased anxiety-like behavior. In the open field, young, non-lactating primiparous animals again exhibited fewer anxiety-like behaviors compared to nulliparous controls, an effect that was reversed in middle-aged animals. Effects of reproductive experience on the EPM in both age groups were eliminated by ovariectomy. Overall, the findings indicate that reproductive experience significantly alters anxiety-like behavior, effects that are influenced by the endocrine status and/or age of the female.